Field of the Invention
This invention relates to a process and an apparatus for the production of gaseous oxygen at high pressure by distillation or air in a double column apparatus comprising a low pressure column and a mean pressure column. The process includes pumping of liquid oxygen withdrawn at the bottom of the low pressure column, and vaporization of the liquid oxygen which is compressed by heat exchange, in a heat exchange line, with air brought to high pressure which is substantially higher than the pressure of the mean pressure column.
The pressures which are maintained below are absolute pressures. The pressures of the mean pressure column and of the low pressure column will hereinafter be called "mean pressure" and "low pressure" respectively.
Processes of this type, known as "pump" processes, render gaseous oxygen compressors unnecessary. To reduce energy expenditure, it is necessary to vaporize a considerable amount of oxygen, of the order of 1.5 times the flow of oxygen to be vaporized, until the pressure achieved is sufficient to liquefy compressed air in counter-current heat exchange.
It is known that the energy expenditure of apparatuses of this type is only lower or equal to that of the apparatuses provided with an oxygen compressor for oxygen vaporization pressures lower than about 10 bars. This energy expenditure progressively increases with pressure. Moreover, in applications where the energy expenditure is acceptable, the usual technology utilizes two compressors mounted in series, the second one treating only the fraction of air intended to vaporize liquid oxygen, which considerably increases the cost of the apparatus.